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Biomedical subjects

N Antoine

Publications and source records attributed to N Antoine.

At least 19 recordsLinked to original sources
PubMed2007

Morphological alterations in oxidative muscles and mitochondrial structure associated with equine atypical myopathy.

REASONS FOR PERFORMING STUDY: There is a lack of well documented studies about muscular lesions in equine atypical myopathy (EAM). OBJECTIVES: To characterise morphopathological changes of striated muscles and myocardium, to progress understanding of this disease. METHODS: Thirty-two horses age 0.5-7 years kept on pasture were referred for a sudden ataxia/myoglobinuria syndrome. Clinical examination (stiffness, muscle pain, muscle fasciculations, abnormal gait, recumbency, myoglobinuria, tachycardia, sweating) and plasma CPK, LDH and AST levels were consistent with extensive myonecrosis and, together with anamnestic data, with so-called 'equine atypical myopathy' (EAM), a disease of unknown aetiology reported since 1939. Macroscopic and microscopic (histology, histoenzymology, ultrastructure) lesions were evaluated. RESULTS: Necropsic examination revealed large areas of muscle necrosis, the extent and severity of which varied between cases and muscles, but which were clearly more constant and severe in respiratory and postural muscles and in the myocardium. Histology highlighted a multifocal and monophasic process compatible with Zenker degeneration/necrosis that mostly and segmentally affected type 1 fibres. Histochemical evaluation revealed a weak and disorganised pattern of NADH tetrazolium reductase staining, the absence of calcium salts precipitates and a dramatic accumulation of lipid droplets. Ultrastructural examination often revealed fibres of which the sole modifications were altered mitochondria and sarcoplasmic lipidosis. CONCLUSIONS: Taken together, the data suggest that a primary alteration of mitochondria should be considered, although secondary mitochondrial abnormalities have yet to be ruled out. POTENTIAL RELEVANCE: The morphological features gathered here reveal that EAM shares most of the characteristics of toxic myopathies.

Animals↗
PubMed2004

FDC-B1: a new monoclonal antibody directed against bovine follicular dendritic cells.

Follicular dendritic cells (FDCs) are a unique population of accessory cells located in the light zone of the germinal centres of lymphoid follicles. Their involvement in the generation of humoral immune responses implies a potential role for these cells in many disorders. Indeed, in prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein expression and the principal sites of the infectious agent accumulation in lymphoid organs. The identification of FDC is useful for the analysis of their distribution in reactive lymphoid tissue as well as in pathological conditions. The production and characterisation of a new mouse monoclonal antibody directed against bovine follicular dendritic cells (FDC-B1) is reported. The antigen detected by FDC-B1 is expressed exclusively on the surface of FDCs in ruminant lymphoid organs. The antigen has an approximate molecular weight of 28 kDa.

Animals↗
PubMed2002

DNA immunisation. New histochemical and morphometric data.

Splenic germinal center reactions were measured during primary response to a plasmidic DNA intramuscular injection. Cardiotoxin-pretreated Balb/c mice were immunized with DNA plasmids encodmg or not the SAG1 protein, a membrane antigen of Toxoplasma gondii. Specific anti-SAG1 antibodies were detected on days 16 and 36 after injection of coding plasmids. The results of ELISAs showed that the SAG1-specific antibodies are of the IgG2a class. Morphometric analyses were done on serial immunostained cryosections of spleen and draining or non-draining lymph nodes. This new approach made it possible to evaluate the chronological changes induced by DNA immunisation in the germinal centres (in number and in size). Significant increases in the number of germinal centres were measured in the spleen and only in draining lymph nodes after plasmid injection, the measured changes of the germinal centers appeared to result from the adjuvant stimulatory effect of the plasmidic DNA since both the coding and the noncoding plasmid DNA induced them. No measurable changes were recorded in the T-dependent zone of lymph organs.

Animals↗
PubMed2001

New histochemical and ultrastructural observations on normal bovine tonsils.

Samples of normal bovine palatine tonsils were examined by light and electron microscopy. Like human tonsils, they were composed of crypts, subepithelial areas, follicles, and T-dependent zones, but their well-developed capsule subdivided the lymphoid tissue by connective septa. B cells formed the major lymphoid component. The follicles and T-dependent zones had morphological and histochemical features typical of peripheral lymph organs. Follicular dendritic cells were isolated and shown to be similar to human follicular dendritic cells.

Animals↗
PubMed2001

The fungal biocontrol agent Coniothyrium minitans: production by solid-state fermentation, application and marketing.

Biological control agents (BCAs) are potential alternatives for the chemical fungicides presently used in agriculture to fight plant diseases. Coniothyrium minitans is an example of a promising fungal BCA. It is a naturally occurring parasite of the fungus Sclerotinia sclerotiorum, a wide-spread pathogen which substantially reduces the yield of many crops. This review describes, exemplified by C. minitans, the studies that need to be carried out before a fungal BCA is successfully introduced into the market. The main aspects considered are the biology of C. minitans, the development of a product by mass production of spores using solid-state fermentation technology, its biocontrol activity and marketing of the final product.

Ascomycota↗
PubMed2001

Isolation of bovine follicular dendritic cells allows the demonstration of a particular cellular prion protein.

As interaction of cellular prion protein (PrPc) and the infectious agent (PrPres) appears to be a crucial pathogenic step promoted by homology, variation in PrPc isoforms on bovine immune cells may explain the absence of infectivity in most bovine lymph organs. In this study, we examined PrPc expression in bovine lymph organs (tonsils and lymph nodes) and on isolated follicular dendritic cells (FDCs). We used a panel of different monoclonal antibodies (MoAbs) raised against different epitopes of prion protein. Two MoAbs recognise amino acids 79-92 (SAF 34 and SAF 32 Mo-Abs); the 6H4 antibody reacts with a specific peptide comprising the 144-152 amino acids, and the 12F10 MoAb recognises the sequence 142-160. After immunolabelling of frozen sections of lymph organs with 6H4 or 12F10 MoAbs, we detected cellular prion protein in germinal centres. However, using the SAF 34 or SAF 32 antibodies, PrPc was revealed outside the lymphoid tissues. No PrPc was observed in the germinal centres. Therefore, we adapted the method of FDC isolation, making it suitable for the study of PrPc expression on their surface. Using electron microscopy, the presence of PrPc on the surface of FDCs was demonstrated only with 6H4 MoAb. These results suggest that bovine follicular dendritic cells express a particular form of prion protein. Either the N-terminal part of PrPc is cleaved or the accessibility of the specific epitope (79-92) of SAF 34 MoAb is abolished by interaction with other molecules. This particular isoform of PrPc on bovine FDCs might be related to the apparent absence of infectivity in lymph organs in cattle affected by bovine spongiform encephalopathy.

Animals↗
PubMed2001

Human FDC express PrPc in vivo and in vitro.

Prion diseases are fatal neurodegenerative disorders caused by accumulation of abnormal prion protein (protease-resistant prion, PrPres). PrPres accumulation is also detected in lymphoid organs after peripheral infection. Several studies suggest that follicular dendritic cells (FDC) could be the site of PrPres retention and amplification. Here we show that human follicular dendritic cells can express normal cellular prion protein (PrPc) both in situ and in vitro. When tonsillar cryosections were treated with anti-PrP antibody, the label was found on some very delicate cell extensions inside the lymphoid follicles, especially in the germinal centres. These extensions react with DRC1 antibody, used frequently to label FDC. Other structures labelled with anti-PrP antibody were the keratinocytes. To confirm the ability of FDC to synthesise PrPc, we isolated FDC by a non-enzymatic procedure and cultured them. By cytochemistry and flow cytometry it was clearly shown that FDC do produce PrPc.

Cells, Cultured↗
PubMed2000

TNP-470, a potent angiogenesis inhibitor, amplifies human T lymphocyte activation through an induction of nuclear factor-kappaB, nuclear factor-AT, and activation protein-1 transcription factors.

TNP-470, an angiogenesis inhibitor derived from fumagillin, is foreseen as a promising anti-cancer drug. Its effectiveness to restrain tumor growth and its lack of major side effects have been demonstrated in several animal models and have led the drug to reach phase III clinical trials. Beside its antiangiogenesis activities, TNP-470 exhibits several effects on the immune system. We had shown previously that TNP-470 stimulated B lymphocyte proliferation through an action on T cells. In this study, we examined the cellular and molecular modifications induced by TNP-470 in normal human T lymphocytes. Transmission electron microscopic examination of PHA/TNP-470-treated T cells revealed significant morphologic modifications when compared with PHA-treated control T cells. TNP-470 induced indeed an important and significant increase of the nuclear size as well as major nuclear chromatin decondensation. This observation indicated that TNP-470 amplified T-cell activation and led us to investigate its effects on the activation of transcription factors involved in T-cell activation. Using electrophoretic mobility shift assays, we have demonstrated that TNP-470 amplifies and extends the DNA-binding activity of nuclear factor-AT, nuclear factor-KB, and activation protein-1 in T cells. Furthermore, the angioinhibin significantly increased the secretion of IL-2 and IL-4. Our data demonstrate that TNP-470 amplifies the activation of T cells. This effect, whose molecular mechanisms remain to be elucidated, has to be taken into account in the assessment of the antitumor effect of the drug.

Angiogenesis Inhibitors↗
PubMed2000

Bone sialoprotein mRNA and protein expression in human multiple myeloma cell lines and patients.

Bone sialoprotein (BSP) is a glycoprotein essentially found in mineralizing connective tissues. We have recently demonstrated that BSP is ectopically expressed by carcinomas that metastasize to bone with high frequency. Multiple myeloma (MM) is characterized by the localization of tumour plasma cells in the bone marrow. In this study, BSP expression was evaluated in human myeloma cell lines and in bone marrow aspirates and one ascites fluid from MM patients. BSP was detectable in conditioned media of MM cell lines. Using FACS analysis and in situ hybridization, we demonstrated that tumour cells from all MM patients and cell lines analysed express BSP at both the protein and the mRNA level.

Bone Marrow↗
PubMed2000

Differential expression of cellular prion protein on human blood and tonsil lymphocytes.

BACKGROUND AND OBJECTIVE: The expression of cellular prion protein (PrPc) on the surface of peripheral lymphocytes has been previously reported, but little is known about its expression on lymphoid cells from secondary lymph organs. In this report, we compare the surface expression of PrPc on human blood lymphocytes and tonsil lymphocytes. DESIGN AND METHODS: This analysis was performed by cytometry on live lymphocytes isolated from healthy donors or from the tonsils of adults or children. RESULTS: Human peripheral lymphocytes and tonsillar lymphoid cells, but not erythrocytes or granulocytes, express PrPc at their surfaces. Interestingly, we found significantly less PrPc on freshly isolated tonsil lymphocytes, both B and T, than on blood cells. Although tonsil cells bear less PrPc than circulating blood lymphocytes, they are able to express high quantities of PrPc on their surface when placed in culture. However, contrary to previous results, mitogen stimulation does not affect this expression on B- or T-cells. INTERPRETATION AND CONCLUSIONS: We suggest that the PrPc expression by lymphocytes may be modified by interactions occurring during intratissular migration or during cell-to-cell contacts. Whether PrPc plays a role in intracellular communication at this location, as it does in the nervous system, remains an open question.

Adult↗
PubMed1996

In vitro and in vivo stimulation of the murine immune system by AGM-1470, a potent angiogenesis inhibitor.

AGM-1470, a potent angiogenesis inhibitor, is already engaged in phase I clinical trials because of its effectiveness to restrain tumor growth and its lack of major side effects. Recently, we showed that AGM-1470 stimulates in vitro human B lymphocyte proliferation through T lymphocytes. These data prompted us to explore the in vivo effects of AGM-1470 on the immune system in a mouse model. In this study, we showed that AGM-1470, in synergy with phytohemagglutinin, stimulates the proliferation of murine lymphocytes isolated from lymph nodes. This effect was similar to the one observed with human lymphocytes. When injected subcutaneously or intraperitoneally into mice at pharmacological doses, AGM-1470 induced a significant increase of axillary and mesenteric lymph nodes, respectively. Histological and morphological analyses showed that this phenomenon is mostly due to a hyperplasia of the germinal centers. On average, the area of the germinal center of lymph nodes from AGM-1470-treated mice were three times larger than in lymph nodes from control mice. Interestingly, no effect was observed when AGM-1470 was injected subcutaneously into T-deficient nude mice. Our data demonstrate that AGM-1470 stimulates B cell proliferation in vivo as suggested by the in vitro experiments. This effect should be taken into account in the follow-up of patients treated with this molecule and calls for additional studies to determine the biological consequences of such a stimulation on the host immune system.

Animals↗
PubMed1996

Detection of bone sialoprotein in human breast cancer tissue and cell lines at both protein and messenger ribonucleic acid levels.

The recent demonstration that bone sialoprotein (BSP) can be detected in human breast cancer tissue by immunoperoxidase suggests that this phosphoprotein is ectopically expressed by malignant mammary epithelial cells. Its detection in human breast cancer cells raises questions about its potential role(s) during breast cancer progression. Because BSP is secreted and is present in the serum, the positivity of breast cancer cells for BSP could have been the result of an uptake of the circulating phosphoprotein by the cells rather than of an intrinsic expression. We examined the expression of BSP at both the protein and mRNA levels in nine human breast cancer samples as well as in three human breast cancer cell lines (MCF-7, T47-D, and MDA-MB-231) using immunohistochemistry, flow cytometric analysis, immunoblot, and reverse-transcriptase PCR. BSP was detected at both protein and mRNA levels in human breast cancer tissue and in the three human breast cancer cell lines. Using a specific polyclonal anti-BSP antibody, we showed by both fluorescence-activated cell sorter analysis and immunohistochemistry experiments that all of the human breast cancer cell lines studied express BSP. This was localized at the cell surface and in the cytosol of the estrogen receptor-positive MCF-7 and T47-D cell lines, whereas it was detected only in the cytosol of the estrogen receptor-negative MDA-MB-231 cells. Using the same polyclonal anti-BSP antibody, we were able to identify an approximately 97-kd band on total protein extracts from the three cell lines by immunoblotting. Reverse-transcriptase PCR reactions using specific oligonucleotides performed on total RNA of nine human breast cancer biopsy samples and the three cell lines demonstrated the presence of BSP mRNA in all of the samples examined. This study is the first demonstration that human malignant breast epithelial cell lines express BSP at the protein and mRNA levels. Our study identified MCF-7, T47-D, and MDA-MB-231 cells as useful models for the examination of the molecular mechanisms involved in the ectopic expression of BSP in breast malignant lesions.

Base Sequence↗
PubMed1995

Tamoxifen and its active metabolite inhibit growth of estrogen receptor-negative MDA-MB-435 cells.

Tamoxifen (TAM), the non-steroidal anti-estrogen most widely administered to breast cancer patients, acts, at least in part, by competing with estrogen receptors (ER). However, the existence of an alternative mechanism of action for this drug is supported by the clinical observations that: (a) 30% of patients with ER-negative cancer cells respond to TAM, and (b) 30% of patients with ER-positive cancer cells are not sensitive to this anti-estrogen. In this study, we observed that growth of the human ER-negative breast cancer cell line MDA-MB-435 was inhibited by TAM and 4-hydroxytamoxifen (4OH-TAM) in a concentration-dependent fashion. Both monoclonal enzymoimmunoassay and Dextran Charcoal Coated Scatchard radioimmunoassay analysis demonstrated that this MDA-MB-435 cell line does not express ER. The absence of ER in MDA-MB-435 cells was also demonstrated at the mRNA level by both northern blot hybridization and reverse transcription-polymerase chain reaction techniques. MDA-MB-435 cell proliferation was not affected by 17 beta-estradiol or by the pure anti-estrogen ICI 164384, further demonstrating that the observed effects of TAM and its active metabolite on the proliferation of MDA-MB-435 cells were due to an ER-independent mechanism, yet to be identified. MDA-MB-435 thus appears to be a promising original model for the study of the alternative ER-independent mechanisms of action of TAM.

Breast Neoplasms↗
PubMed1994

AGM-1470, a potent angiogenesis inhibitor, prevents the entry of normal but not transformed endothelial cells into the G1 phase of the cell cycle.

AGM-1470 is a potent angiogenesis inhibitor that is very effective in inhibiting endothelial cell proliferation in both in vitro and in vivo models and that prevents tumor growth in vivo. Although this molecule appears to be a most promising anticancer drug, its mechanism of action has not yet been elucidated. In this study, we examined the effects of AGM-1470 on the cell cycle of normal and transformed endothelial cells. We showed that AGM-1470, at picomolar concentrations, specifically inhibits the proliferation of both bovine aortic endothelial cells and human umbilical vein endothelial cells. AGM-1470 was ineffective in significantly inhibiting the proliferation of Ea.hy926 cells, a hybrid cell line obtained by the fusion of human umbilical vein endothelial cells with a human carcinoma cell line, or cEnd.1 cells, a polyoma middle T oncogene-transformed endothelioma cell line derived from mouse embryo. Using a double labeling technique with anti-Ki67 antibodies and propidium iodide, we demonstrated, with flow cytometry analysis, that AGM-1470 specifically prevents the entry of endothelial cells into the G1 phase of the cell cycle. We also showed that AGM-1470 was ineffective in inhibiting endothelial cell migration toward laminin or capillary-like tube formation inside a type I collagen matrix induced by phorbol esters. Our data strongly suggest that AGM-1470 is a molecule that specifically inhibits a cell cycle control pathway active in normal cells but which could be bypassed or altered in transformed cells.

Animals↗
PubMed1994

Moabs MAS516 and 5B5, two fibroblast markers, recognize human follicular dendritic cells.

Follicular dendritic cells (FDC) are only located within follicles of secondary lymphoid tissues. The origin of this peculiar cell type is not clearly defined. To contribute to this study, we applied two monoclonal antibodies (MAS516 and 5B5) considered as specific for fibroblasts to tonsil cryosections and to isolated follicular dendritic cells. On the basis of an enzyme cocktail digestion of human tonsils and a fractionation procedure on albumin gradients, FDC can be prepared in the form of cell aggregates with associated lymphoid cells. MAS516 reacts with surface membrane molecules expressed by human fibroblasts, tissue macrophages and peripheral blood monocytes. With immunoperoxidase assays on tonsil cryosections connective tissue cells and macrophages are stained. Inside germinal centres, heavy labelling of the light zone was found. The MAS516 staining pattern is very similar to that of specific FDC markers DRC-1 or BU10. All isolated FDC reacted with MAS516 antibody. 5B5, considered as a typical fibroblast marker, reacts with human prolyl-4-hydroxylase which is an intracellular enzyme related to collagen biosynthesis. In cryosections, interfollicular and capsular areas showed 5B5 positive connective tissue fibroblasts. In germinal centres, some cells presenting features of FDC were 5B5 positive. After cell separation, 25%-50% of the isolated FDC were labelled with this antibody. This positivity of some FDC for 5B5 antibody may support the idea of their fibroblastic origin. The combination of observations realized in situ and after cell purification ensured an unequivocal recognition and identification of FDC.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗